RELATED APPLICATIONS

001 This application claims the benefit of priority to U.S. Application Serial Number 62/240,642 filed October 13, 2015 the disclosure of which in incorporated by reference in its entirety as if fully set forth herein.

002 The disclosures of all of the following are incorporated by reference in their entirety as if fully set forth herein: PCT/US2012/067379 filed November 30, 2012, PCT/US2013/053591 filed August 5, 2013, U.S. Patent No. 5,894,025, U.S. Patent No. 6,062,840, U.S. Patent No.

6,294,122, U.S. Patent No. 6,309,208, U.S. Patent No. 6,287,107, U.S. Patent No. 6,343,921, U.S. Patent No. 6,343,922, U.S. Patent No. 6,254,377, U.S. Patent No. 6,261,075, U.S. Patent No. 6,361,300 (7006), U.S. Patent No. 6,419,870, U.S. Patent No. 6,464,909 (7031), U.S. Patent No. 6,599,116, U.S. Patent No. 7,234,929 (7075US 1), U.S. Patent No. 7,419,625 (7075US2), U.S. Patent No. 7,569,169 (7075US3), U.S. Patent Application Serial No. 10/214,118, filed August 8, 2002 (7006), U.S. Patent No. 7,029,268 (7077US 1), U.S. Patent No. 7,270,537 (7077US2), U.S. Patent No. 7,597,828 (7077US3), U.S. Patent Application Serial No.

09/699,856 filed October 30, 2000 (7056), U.S. Patent Application Serial No. 10/269,927 filed October 11, 2002 (7031), U.S. Application Serial No. 09/503,832 filed February, 15, 2000 (7053), U.S. Application Serial No. 09/656,846 filed September 7, 2000 (7060), U.S.

Application Serial No. 10/006,504 filed December 3, 2001, (7068), U.S. Application Serial No. 10/101,278 filed March, 19, 2002 (7070) and international applications PCT/US2011/062099 and PCT/US2011/062096.

SUMMARY OF THE INVENTION

003 According to various embodiments of the invention, methods and apparatuses are provided for monitoring the position of a valve pin with a sensor and generating a visual display of data relating to the position and to the rate of travel of the pin between closed and open positions. The methods include controllably adjusting the valve pin poisition by issuing commands to an actuator to alter the pin position, monitoring the pin position via a sensor, and processing the sensor output to determine the effect of such commands on the valve pin position, including opening time and opening speed. A valve monitoring interface is provided that enables valve gate monitoring in a visual format. The interface is positionable outside of the mold tool, for ease of access by the user.

004 With the valve monitoring interface (VMI) a human operator (user) can check that the actuators are driving the valve pins according to a desired program of valve gate opening and closing times of the respective mold cavity gates, and also compare the valve pin velocities during the molding process. It enables the user to confirm during a set up period, e.g., when either a new mold is positioned in the machine, or a new control program is provided, that the individual valve pins feeding each gate of the mold are functioning according to the desired program control. In one embodiment, a position sensor is installed on each actuator and sends a piston position signal to a junction box. The data from these signals is transferred from the junction box to a main monitor at which it is displayed visually. In one embodiment, green/yellow/red LED lights convey the respective open/intermediate/closed position status data.

005 In another embodiment, a visual (e.g., LCD) display shows the time taken for the respective valve pin to move from the closed to the open position for a respective valve pin with respect to its associated gate.

006 In another embodiment, the visual display shows the opening speed for the valve pin to move from the closed to the open position for a respective valve pin with respect to its associated gate.

007 According to one embodiment of the invention there is provided an injection molding system (10) comprising:

a sequential multi- valve gated mold (502), in which each one of a plurality of valve pins (21) is driven by an actuator (20, 52) to open and close an associated one of a plurality of gates (23) into a mold cavity (500),

a controller (51) having instructions issuing commands to the actuators (20, 52)) to drive each of the valve pins (21) to open and close its associated gate (23),

a position sensor (30, 52) associated with each valve (21) for monitoring the position of the valve pin with respect to the gate (23) along a path of travel between an open position and a closed position of the valve pin with respect to the associated gate,

wherein the actuators (20, 52) associated with each valve pin (21) receives commands from the controller (51) to controllably position an associated valve pin (21) with respect to an associated gate (23) along the path of travel, a sensor circuit (92) that receives as input a signal from an associated position sensor (30, 52, 94A, 94B) indicative of position of an associated valve pin (21) as said valve pin moves along the path of travel, the circuit (92) including a processor for processing the input signal to determine output data comprising an opening time and an opening speed of the valve pin with respect to an associated gate (23) based upon the input signal,

an electronic display (61) receiving the output data and generating a visual numeric indication of the opening time and opening speed for each valve pin of the sequential multi-valve gated mold.

006 In such an apparatus the processor can include instructions that process the input signal to generate output data comprising position of each valve pin in at least one or more of a selected upstream position, a downstream gate closed position and any position intermediate the selected upstream and the downstream gate closed positions, the apparatus further comprising a visual display that receives the sensor output signals and includes one or more devices that generate a visually recognizable format indicative of the position of each valve pin in at least one or more of the selected upstream positions (40G), the downstream gate closed position (40R) and any position intermediate the selected upstream and the downstream gate closed positions (40Y).

007 In such an apparatus the visual display can comprise one or more devices that display a different visible color unique to each of the one or more selected upstream positions (40G), the downstream gate closed position (40R) and any position intermediate the selected upstream and the downstream gate closed positions when a pin is disposed in each of said positions (40Y).

008 In such an apparatus the different colors are preferably green for the selected upstream position, yellow for an intermediate position, and red for the downstream gate closed position.

009 In another aspect of the invention there is provided a method of monitoring position and movement of a valve pin (21) in an apparatus (10) as described above comprising operating said apparatus (10) to generate and display the output data in a visually recognizable format indicative of the opening time and the opening speed of each valve pin and indicative of the one or more selected upstream positions (40G), the downstream gate closed position (40R) and any position intermediate the selected upstream and the downstream gate closed positions.

In another aspect of the invention there is provided A method of monitoring valve pin positioning in an injection molding system (10) comprising: controllably adjusting, according to commands issued by a controller (51) to an associated respective actuator (20, 52), the position of an associated valve pin (21) with respect to its associated gate (23) along a path of travel;

monitoring, via a sensor (30, 55), the position of an associated valve pin (21) while the valve pin moves along the path of travel between a closed position, sealing the associated gate (23), to an open position, allowing fluid to flow through the gate;

generating, via a sensor circuit (92), output data indicative of the valve pin opening time and opening speed;

displaying, via an electronic display (61), the output data from the sensor circuit (92) in a visually recognizable numeric format indicative of the valve pin opening time and opening speed.

0010 In such an embodiment the controller includes instructions that can issue a command to at least one actuator for the valve pin to open the associated gate, and the method includes generating and displaying the output data and monitoring the display to confirm the subsequent opening time or opening speed of the associated gate.

0011 The controller includes instructions that can issue commands to the plurality of actuators for the plurality of valve pins to open the associated gates in a timed sequence of valve pin openings, and the method includes generating and displaying the output data and monitoring the display to confirm the subsequent opening time or opening speed of the associated gates according to the timed sequence.

0012 A flow controller is typically provided for altering the fluid pressure in a valve pin channel associated with the valve pin, the flow controller issues a command to alter the fluid pressure in the channel, and the method includes generating and displaying the output data and monitoring the display to determine the subsequent effect of the command on the opening time or opening speed of the associated gate.

0013 The controller can issue commands to the plurality of actuators to open the plurality of valve pins in accordance with designated pin opening speeds, and the method includes generating and displaying the output data and monitoring the display to confirm the subsequent opening speeds of the associated gates.

0014 The method typically further comprises mounting the display on a machine side of an injection molding system. 0015 The method can further comprise formatting the display to include a display of output data for a selectable gate and associated valve pin.

0016 The display format can comprise an LCD display showing one or more of the opening time and opening speed.

0017 The method can be used as a diagnostic tool for troubleshooting a hot runner component of the injection molding system.

0018 The method can be used for preventive maintenance of a hot runner component of the injection molding system.

0019 The method can be used for process set-up of a hot runner component of the injection molding system.

0020 The display can be removably coupled to the sensor circuit output.

0021 The sensors typically comprise one of more hall effect sensors for an associated valve pin.

0022 The method can further comprise formatting the display to include, in real-time for each valve pin, a visually recognizable indicator of position status comprising one of open, closed and intermediate positions.

0023 In another aspect of the invention, there is provided in an injection molding system comprising a sequential multi-valve gated mold, in which each one of a plurality of valve pins is driven by an actuator along a path of travel extending between a selected upstream-most open position and a downstream-most gate closed position to open and close an associated one of a plurality of gates into the mold cavity;

a controller issuing commands to the actuators to drive each of the valve pins to open and close its associated gate;

a position sensor associated with each valve pin for monitoring a position of the valve pin along the path of travel;

the actuator associated with each valve pin receiving commands from the controller to controllably position the valve pin along the path of travel;

a sensor circuit that receives as input a signal from the sensor indicative of the position of the valve pin and a processor for processing the input signal to generate an output signal;

a display receiving the output signal and generating a visual display indicative of pin position along the path of travel for each valve pin; 0024 In another aspect of the invention there is provided a method of monitoring valve pin positioning comprising:

controllably adjusting the position of the actuator along the path of travel;

monitoring the position of the valve pin via the sensor along the path of travel; generating the output signal indicative of pin position along the path of travel for each valve pin;

displaying in a visually recognizable format the pin position along the path of travel for each valve pin, wherein the format comprises three different visible lights, each indicative of a different one of the valve pin positions comprising the selected upstream-most open position, the downstream-most gate closed position, and an intermediate position between the open and closed positions.

0025 In such a method the different visible lights are preferably of different colors.

0026 The different colors are preferably green for the open position, yellow for the intermediate position, and red for the closed position.

0027 The step of displaying can further comprise displaying an opening time.

0028 The step of displaying can further comprise displaying an opening speed.

0029 The method can further comprise programming the controller to send a command to at least one actuator for the valve pin to open the associated gate.

0030 The method can further comprise programming the controller to send a command to the plurality of actuators for the plurality of valve pins to open the associated gates in a timed sequence of valve pin openings.

0031 The method can further comprise programming the controller to send a command to all but one of the actuators for the valve pin to close the associated gate.

0032 The method can further comprise programming the controller to send a command to the actuator to move the valve pin to an open position, and a user monitors the display to confirm that the respective valve pin is open.

0033 The method can further comprise programming the controller to send a command to the plurality of actuators for the valve pins to open the gates in a timed sequence, and a user monitors the display to confirm the openings of the respective gates according to the timed sequence. 0034 In such a method a flow controller is typically provided for altering the fluid pressure in a valve pin channel associated with the valve pin, the flow controller receives a command to alter the fluid pressure in the channel, and the user monitors the display to monitor the effect of altering the fluid pressure on the opening speed of the associated valve pin.

0035 The method can further comprise programming the controller to send a command to the plurality of actuators to open the plurality of valve pins in accordance with designated pin opening speeds, and a user monitors the display to confirm whether the valve pins open according to the designated pin opening speeds.

0036 In another aspect of the invention, there is provided a method of monitoring valve pin positioning comprising:

interconnecting each one of a plurality of valve pins to an associated one of a plurality of actuators and driving each actuator to drive each associated valve pin along a path of travel extending between one or more selected upstream positions and a downstream gate closed position for each valve pin to open and close a plurality of associated gates into a mold cavity; continuously monitoring a position of each valve pin along the entirety of the path of travel via a position sensor associated with each actuator that detects the position along the entirety of the path of travel of each valve pin,

generating a sensor output signal from the sensor indicative of the position of each valve pin along the entirety of the path of travel between the downstream gate closed position and the one or more selected upstream positions,

generating a visual display based on the sensor output signals, in a visually recognizable format indicative of valve pin position along the path of travel for each valve pin.

0037 In such a method the visual display can comprise a different visible color unique to each of the selected upstream position, the downstream gate closed position and any position intermediate the selected upstream and the downstream gate closed positions.

0038 The different colors are preferably green for the selected upstream positions, yellow for an intermediate position, and red for the downstream gate closed position.

0039 The step of displaying can further comprise displaying an opening time for each valve pin to travel from the downstream gate closed position to the one or more selected upstream positions. 0040 The step of displaying can further comprise displaying an opening speed for each valve pin in travelling from the downstream gate closed position to the one or more selected upstream positions.

0041 In another aspect of the invention there is provided a method of monitoring valve pin positioning comprising:

interconnecting each one of a plurality of valve pins to an associated one of a plurality of actuators and driving each actuator to drive each associated valve pin along a path of travel extending between one or more selected upstream positions and a downstream gate closed position to open and close a plurality of associated gates to a mold cavity;

monitoring position of each valve pin along the path of travel via a position sensor associated with each actuator,

generating a sensor output signal from the position sensors indicative of the position of each valve pin between the downstream gate closed position and the one or more selected upstream positions,

generating a visual display based on the sensor output signals, in a visually recognizable format indicative of the position of each valve pin in at least one or more of the selected upstream positions, the downstream gate closed position and any position intermediate the selected upstream and the downstream gate closed positions.

0042 The step of generating preferably comprises displaying a different visible color unique to each of the selected upstream positions, the downstream gate closed position and any position intermediate the selected upstream and the downstream gate closed positions when a pin is disposed in each of said positions.

0043 The different colors most preferably are green for the selected upstream positions, yellow for an intermediate position, and red for the downstream gate closed position.

0044 The step of generating typically further comprises calculating an opening time from the sensor output signals for each valve pin.

0045 The step of displaying typically further comprises displaying the opening time for each valve pin to travel from the downstream gate closed position to the one or more selected upstream positions.

0046 The step of generating typically further comprises calculating an opening speed from the sensor output signals for each valve pin. 0047 The step of displaying further comprise displaying an opening speed for each valve pin in travelling from the downstream gate closed position to the one or more selected upstream positions.

0048 Preferably the step of monitoring includes sensing and monitoring the position of a valve pin at all positions between and including the downstream gate closed position and the one or more upstream positions. And the step of generating typically includes displaying the position of a valve pin at all positions between and including the downstream gate closed position and the one or more upstream positions.

0049 In another aspect of the invention there is provided an apparatus for monitoring valve pin positioning in an injection molding apparatus comprised of a plurality of valve pins each interconnected to an associated one of a plurality of actuators that drive each associated valve pin along a path of travel extending between one or more selected upstream positions and a downstream gate closed position to open and close a plurality of associated gates to one or more mold cavities, wherein the apparatus comprises;

a plurality of position sensors associated with each valve pin that monitor the position of each valve pin between and including the downstream gate closed position and the one or more upstream positions,

each position sensor generating a sensor output signal indicative of the position of each valve pin,

a visual display that receives the sensor output signals and includes one or more devices that generate a visually recognizable format indicative of the position of each valve pin in at least one or more of the selected upstream positions, the downstream gate closed position and any position intermediate the selected upstream and the downstream gate closed positions.

0050 The visual display preferably comprises one or more devices that display a different visible color unique to each of the one or more selected upstream positions, the downstream gate closed position and any position intermediate the selected upstream and the downstream gate closed positions when a pin is disposed in each of said positions.

0051 The different colors most preferably are green for the selected upstream positions, yellow for an intermediate position, and red for the downstream gate closed position.

0052 The apparatus preferably includes a controller that includes a program that calculates an opening time from the sensor output signals for each valve pin. And, the visual display preferably includes a device that receives and displays the calculated opening time in a visually recognizable format.

0053 The controller preferably includes a program that calculates an opening speed from the sensor output signals for each valve pin. And, the visual display preferably includes a device that receives and displays the calculated opening speed in a visually recognizable format.

0054 Preferably the position sensors sense the position of a valve pin at all positions between and including the downstream gate closed position and the one or more upstream positions. And the visual display typically includes a device that displays the position of a valve pin at all positions between and including the downstream gate closed position and the one or more upstream positions. The position sensors typically comprise a Hall Effect Sensor.

BRIEF DESCRIPTION OF THE FIGURES

0055 Fig. 1 is a schematic illustration of an injection molding system with a valve monitoring interface (VMI) unit mounted thereon;

0056 Fig. 2 is a schematic illustration of a hot runner system including a position sensor for monitoring valve pin position according to one embodiment, whrein the sensor output is fed to an LED display that provides different colors of light to indicate the valve position as one of open, closed, and intermediate (between open and closed);

0057 Fig. 3 is a schematic illustration of a hot runner system feeding a four cavity mold according to one embodiment of the invention;

0058 Fig. 4 is a schematic illustration of four positions sensors, each mounted on a different one of four actuators, for sending output signals to a VMI unit for display of valve pin position as one of open/closed/intermediate, and also the opening time and opening speed, according to one embodiment of the invention;

0059 Fig. 5 is a schematic illustration of a display of opening time, showing the time elapsed for an actuator and an associated valve pin to move from a lowermost closed position to an uppermost open position;

0060 Fig. 6 is a schematic illustration of a valve monitoring interface unit according to one embodiment, including an LCD display of opening time and opening speed, and LED pin status indicators; and 0061 Fig. 7 is a schematic illustration of one embodiment showing a valve pin in a nozzle channel for feeding fluid to a mold cavity, a driving actuator, position sensor, junction box and valve monitoring interface, as an interconnectable assembly.

DETAILED DESCRIPTION

0062 The invention will now be described with regard to various embodiments illustrated in Figs. 1-7. These embodiments are illustrative of various features of the invention, and are not limiting.

0063 Fig. 1 shows an injection molding system 10 in which a valve monitoring interface (VMI) unit 12 is mounted on the "machine side" 13 and is electronically coupled via a connector 14 to a junction box 15 mounted on the "tool side" 16 of the machine. An extruder 17 feeds molten fluid (e.g. metal or plastic) to a hot runner system 18 for feeding the melt to one or more mold cavities on the "tool side." In one embodiment, the mold cavity is a sequential multi- valve gated mold, in which each of a plurality of valve pins is driven by an actuator to open and close an associated one of a plurality of gates into the mold cavity. Typically the opening and closing of such gates is accomplished by a controller issuing commands to the actuators to drive each of the valve pins to open and close with respect to its associated gate, according to a timed sequence. The opening speed, by which the valve pin is withdrawn from the gate, may be a total average speed from the downward-most fully closed position to the uppermost open position. Alternatively, a plurality of different valve opening speeds between the lowermost fully closed and uppermost open valve pin positions may be designated, in serial order, for a given valve pin, and then monitored, processed and displayed in serial order. The present invention is particularly useful for monitoring valve pin position in a sequential multi- valve gated mold (see Fig. 3), as it enables a human operator to visually monitor the opening and closing of each of a plurality of valve pins that feed melt to the mold cavity, according to a timed sequence of valve pin openings, while also allowing the operator to monitor the opening time and opening speed of each actuator, as described more fully below.

0064 Fig. 2 illustrates a series of different colored indicator lights 40, that are provided on a VMI interface unit 60 as shown in Figs. 4 and 6-7, for each of a plurality of valve pins feeding a mold cavity. Fig. 2 shows schematically on the left a hot runner system 18 in which one of a plurality of actuators 20 and an associated valve pin 21 is illustrated in cross section, the valve pin 21 extending through a nozzle channel 22 for feeding fluid into a gate 23 of the mold cavity. A position sensor 30 is mounted on the actuator 20 to detect the relative position of the head 24 of the actuator piston 25, and thus the position of its associated valve pin 21, that is driven linearly by the actuator piston. In one embodiment, a sensor system may be used as described in Tan US Patent 9,144,929, issued 29 September 2015, incorporated by reference in its entirey, and attached hereto as Appendix A. In other embodiments, different sensor systems can be used. The sensor sends an output signal that is ultimately displayed on the VMI unit 60 (see Fig. 4) as an LED pin status 40, one for each valve pin and its associated gate. In this embodiment, the LED output is green 40G when the piston (and associated valve pin) is in the uppermost open position, yellow 40Y when the piston (and associated valve pin) is in an intermediate position between the uppermost position and the lowermost position, and red 40R when the piston (and associated valve pin) is in the downstream most fully closed position.

0065 Fig. 3 is a schematic illustration of a ten drop sequentially valve gated hot runner system 50, for feeding a four cavity mold. This type of mold is suitable for molding metal automobile body parts, such as door moldings. A controller 51, coupled to the actuators 52, issues commands for moving the actuators to drive their associated valve pins 53 along a predetermined path of travel, from a lowermost fully closed position to an uppermost fully open position. A junction box 54 receives signals from the position sensors 55 associated with each of the actuators, for receiving the sensor output and relaying the same to the VMI unit 60 (of Figs. 4 and 6-7). The VMI unit may be removably connected to the junction box 54 by an electronic cable 74 with removable connectors on each end (see Fig. 7), thus allowing the VMI unit 60 to be used on any one of a number of different injection molding systems as the need arises. In this example (see Fig. 4), the VMI 60 receives output signals 58 from each of the sensors 55 (via the junction box) to enable an operator to visually observe, from the LED position lights 40, that all of the valve pins 53 are opening according to a predetermined program, and their opening time and opening speed, as indicated on a visual numeric LCD display 61, in accordance with a predetermined acceptable range of opening time and speed. In one example, when defective parts are observed for a particular injection molding system, the VMI can be connected to the system to determine whether or not the actuators and valve pins are the source of the problem. If the operator can confirm that the actuators and valve pins are operating (opening) according to the desired opening time and speed, then the operator can rule out the valve pins and actuators as a source of the problem (part defect) and instead consider other variables of the system as the source of the problem.

0066 Figs. 4-7 illustrate one embodiment of a VMI 60 unit as used in the methods of the present invention. Fig. 4 illustrates, on the left, the VMI unit 60 receiving output signals 58 from four position sensors 55, one installed on each of the actuators 52 illustrated on the right side of the figure. The sensor output is fed to the VMI unit 60 to provide a real time visual indication, via the LED color coded display lights 40 on the front panel 62 of the VMI unit. Each LED light 40 is labeled with a number (1, 2...24) corresponding to its associated valve pin and gate (1,

2...24). The VMI unit further includes an LCD display 61 for a selected number of gates, indicated by zone number 63, for showing either the opening speed or the opening time 64 of the associated valve pin 53. A particular zone 63 can be selected by either a line select button 65 on the left, or by toggling either of a zone up button 67 or a zone down button 66 on the right side of the display 61.

0067 Fig. 5 illustrates schematically one example of LCD display 61 showing opening times for two zones, numbers 6 and 4, namely 4.30 and 4.68 seconds respectively. The opening time in this example is the time in seconds (as exemplified by the stopwatch S) for the actuator piston head to move from the fully closed downward-most position shown on the left, to the fully open upward-most position shown on the right.

0068 Figs. 6-7 illustrate one embodiment of the invention. As shown in the assembly of components in Fig. 7, an actuator piston 25 drives a valve pin 53 in a channel 72 of nozzle 70. The nozzle feeds one gate 23 of a mold cavity 24 in a sequential multi- valve gated mold 26. The valve pin is driven by the actuator along the path of travel (illustrated by arrow A) extending between a selected upstream-most position (defined by position U of piston head 24) and a downstream gate closed position (defined by position D of piston head 24) to open and close the associated gate 23 into the mold cavity 24. When open, the fluid in the nozzle channel is allowed to flow into the mold cavity.

0069 The actuator piston is driven by a control valve 80, such as a directional control valve 82, e.g., solenoid; alternatively, it can be driven by a directional control valve 82 in combination with a flow restrictor 81, such as a mechanical or manually adjustable flow restrictor. 0070 A position sensor 55 is mounted on the outer surface of the actuator housing 57. In one embodiment, the sensor comprises one or more hall effect sensors and associated processing circuitry for monitoring the position of the piston, and thus the associated position of the valve pin, between the upstream-most open position and the downstream-most gate closed position. In one embodiment (see e.g., Tan US Patent 9,144,929, Appendix A) the piston includes a magnetic member 90 mounted in the piston head 24 such that axial movement (see arrow A) of the piston 25 in the axial bore 59 of the actuator housing 57 modifies the magnetic field according to the position of the piston head 24 relative to the position sensor. As shown in Fig. 7, hall effect sensor circuit 92, including one or more hall effects sensors, is attached to the exterior surface of a substantially nonmagnetic and/or magnetically permeable body portion of actuator housing 57, wherein the sensor circuit detects the position of the piston relative to the sensor position on the body portion of the actuator housing by detecting the magnetic field of the magnetic member 90 as modified by axial movement of the piston in the bore, and generates a changing output signal that is unique to each travel position of the piston in the bore based on the detected modified magnetic field. In one embodiment, the magnetic member has a north pole end and a south pole end, defining a north-south axis, and the magnetic member's north-south axis is disposed transverse to the direciton of axial movement (A) of the piston in the bore. The hall effect sensor is disposed adjacent either the north pole end or the south pole end of the magnetic member. In one embodiment, a first sensor 94 A is disposed adjacent an uppermost position (U) of the piston, and a second sensor 94B is disposed adjacent a lowermost position (D) of the piston. The outputs of the two sensors may be combined to produce a single signal output indicative of the valve pin position with respect to the gate. In one example, an analog output of one HES sensor 94A disposed adjacent the uppermost position U of the piston (e.g. 0mm position) is combined with an inverted output signal of the second HES sensor 94B, positioned at the (e.g. 20mm) lowermost piston position D, wherein the addition of the output signal of the first sensor and inverted output signal of the second sensor along the path of travel (from 0 to 20 mm) comprises a single continuous output signal that is indicative of each unique position along the path of travel and enables continuous monitoring of the piston position.

0071 In Fig. 7, the output from the position sensor circuit 92 is sent to the junction box 54, and subsequently relayed to the VMI unit 60. The VMI unit includes a series of LED indicater lights 40, one for each of the gates of an associated mold cavity, each gate having an associated valve pin. The LED lights may be numbered, wherein the gate is identified by the associated LED light number. Each of the numbered lights, when the unit is operative, will visually indicate the associated valve pin position at least with respect to three positions: e.g. a first color (e.g. green) for the open position; a second color (e.g. yellow) for an intermediate position between the open and closed position; and a third color (e.g. red) for a closed position. The connection 74 between the VMI controller or unit and junction box 54 can provide both open and closed loop signals to other equipment such as a data logger in order to capture pin opening measurement data for all zones for quality control and other purposes. The VMI controller or unit 60 typically includes a display that provides status indication from a distance.

0072 The VMI also includes an LCD display 61 for visually displaying the valve pin opening time and/or valve pin opening speed for one or more respective valve pins and their associated gates. In addition the VMI can includes a display (40) displaying an electronically generated visual display of a valve open position 40G (green), valve closed 40R (red) and valve intermediate position 40Y (yellow) display 40.

0073 In one embodiment, the VMI can be used to facilitate setting up a valve pin opening speed in conjunction with the use of a mechanical flow restrictor 81 for varying the amount of fluid pressure provided in the nozzle channel 72. In this scenario, a user can adjust the flow restrictor 81 and then use the VMI 60 to monitor the impact, of adjusting the hydraulic flow through the mechanical flow restrictor, to determine the impact on valve pin speed as displayed by the VMI.

0074 In another embodiment, a user can monitor the VMI to determine whether all of the actuators are properly driving the valve pins to open and close the gates according to a predetermined sequence. This could be used as part of an initial start up of the tool, or after service has been completed on the tool. By monitoring the opening and closing lights 40 on the VMI display, while a separate controller 51 commands various pins to open and close, the user can determine whether each actuator is controlling the valve pin as desired, or whether there is a malfunction in the actuator or other aspect of the nozzle or valve pin.

0075 In another embodiment, a user can confirm that a specific valve pin is opening as desired by monitoring the opening and closing lights 40 on the VMI display, while a separate controller 51 commands the various pins to open and close. This can be used as part of an intial start up of the tool, or after any service has been completed to the tool. 0076 In another embodiment, a user can confirm that all actuators are moving at a desired speed as determined by a production process. In this case, the user can monitor the opening speed, either by viewing the opening times for each pin that can be toggled through in the VMI display 61, or via a data logger connected to the VMI display. Again this can be done as part of a preventive maintenance process in order to detect, for example, a slower opening speed which may be due to excessive wear of the valve pin, the valve pin bushing, or the actuator seal.

0077 Thus, in one example the user initiates commands to the actuator (via the controller) to move to an open position, and the user monitors the VMI to confirm the gate is open.

0078 In anther example a user enters a pin opening sequence, and then monitors the VMI to confirm that the plurality of gates are opening according to the predetermined sequence.

0079 In another example a user may adjust a hydraulic flow through a mechanical flow restricter, and then monitor the VMI to determine the impact on opening speed of the valve pin due to the adjustment of hydraulic flow feeding the respective actuator.

0080 In another example, a user can establish the pin opening speeds, and then monitor the VMI to confirm that the respective pins are opening according to the established pin opening speed.

0081 The above embodiments and examples are illustrative of the invention and not meant to be limiting.